The feeding of a liquid enteral nutritional product from a hangable container, such as a bottle or a plastic bag with a bottom outlet connecting to a drip chamber and the latter to a flexible tubing, or lumen, leading to a nasogastric tube or a feeding tube inserted through a gastrostomy or a jejunostomy, by gravity flow or aided by a pump, is well known. The liquid enteral nutritional product may be aseptically processed or terminally retorted, and may be supplied in a pre-filled, ready-to-hang container, or placed in such a container by a caregiver. However, the selection of diets, particularly special diets, from amongst the rather modest number of typically available liquid enteral nutritional products is limited. This narrows, as a practical matter, the choices of the attending physician as to diet modifications, temporary or long term, that might significantly benefit the patient. In view of the now-recognized importance of providing aseptic nutritional compositions, it can be seen that modified diets are not easily prepared without observing the stringent requirements needed to deliver an aseptic nutritional composition to the patient. The need to observe such requirements has heretofore militated against preparing small quantities of special diets designed for a specific patient.
Moreover, a number of nutrients as well as medicaments, diagnostic agents, and other ingredients such as probiotics, that at any given time might be desirable to orally administer to a patient are not stable during heat sterilization or may not be mutually compatible with other desired ingredients for an extended period of time, such as days or even months until used, and thus are not readily amenable to large scale preparation and consequent storage as the product moves through commerce.
Drug delivery systems have been described and claimed in U.S. Pat. Nos. 4,511,353, 5,318,558 and 5,324,280 in which the drug component to be delivered is stored in a capsule from which it is ejected over time upon osmotic infusion of moisture into the capsule, the drug being carried away from the outside surface of the capsule by a suitable liquid in an intravenous, i.e., parenteral, delivery system, or even, by the device of U.S. Pat. No. 5,318,558, by body fluids upon implantation of the capsule.
In U.S. Pat. No. 5,069,671 there is described a formulation chamber, which may also be a drip chamber, in which various forms of sustained release mechanisms are employed to release a drug or medicament, or other physiologically beneficial component such as a nutrient, within the formulation chamber from which the drug or other component is carried by a suitable liquid into a parenteral delivery system.
The teachings of U.S. Pat. Nos. 4,511,353 and 5,069,671 are directed to intravenous delivery of parenteral compositions, and in the case of the latter patent, includes delivery by infusion through intravenous, intraarterial, intraperitoneal or subcutaneous routes. The osmotic dosage system of U.S. Pat. No. 5,324,280 is concerned with the delivery of drug formulations over time to a biological environment, such as a tissue or organ implant in a mammal, or a stream or tank for marine life. The osmotically driven device of U.S. Pat. No. 5,318,558 is said to be usable to deliver drugs, medicaments and nutrients in a range of environments extending from veterinary medicine to human drug administrations, and to hobby situations such as fish tanks. Again, in the case of human administration, the delivery appears to be within a tissue or organ implant.
Although the osmotic delivery devices and other forms of sustained or controlled release dosage forms or reservoirs have been known for some time, so far as is known, there has been no attempt to utilize such a delivery system to add one or more nutrients, or one or more medicaments, or a mixture of nutrients and medicaments, or a probiotic, or a diagnostic agent, or any of these in admixture with a marker dye, to a liquid enteral nutritional product, with a viscosity up to 300 cps., during the administration of the nutritional product to the gastrointestinal tract of a patient. Liquid enteral nutritional products currently on the market are described in the reference text "Nutrition In Critical Care", Gary P. Zaloga, ed., Mosby--Year Book Inc., St. Louis, Mo., 1994, at Chapter 24, authored by Barbara Hopkins, Part III, "Feeding", pp. 439-467. This reference indicates that complete nutrient compositions contain proteins, carbohydrates, fibers, fats, and vitamins and minerals in various proportions in an aqueous or aqueous/fat medium. Nutrient compositions for special diets may omit one or more classes of these components.